Stabilization of hydrocarbons



States ate 3,653,682 Patented Sept. 11, 1962 free 3,053,682 STABILIZATION F HYDROCARBONS Joseph A. Chenicek, Prairie View, and Robert H. Rosenwald, Western Springs, 111., assigncrs to Universal Oii Products Company, Des Plaines, 111., a corporation of Delaware No Drawing. Filed Oct. 30, 1959, Ser. No. 849,714

Claims. (Cl. 106--270) This application is a continuation-impart of copending application Serial No. 617,210, filed October 22, 1956, now Patent No. 2,918,361, which, in turn, is a continuation-in-part of application Serial No. 425,755, filed April 26, 1954, now abandoned, and relates more particularly to a novel method of preventing and/ or retarding deterioration of hydrocarbons.

While the novel features of the present invention are particularly useful in the stabilization of gasoline, they also have particular utility in the stabilization of higher boiling hydrocarbons including, for example, naphthas, kerosene, mineral oil, lubricating oil, cutting oil, rolling oil, electrical oil, insulating oil, hydraulic oil, transmission oil, transformer oil, steam turbine oil, diesel oil, burner oil, fuel oil, petroleum greases, petroleum waxes, petrolatum, etc. As will be hereinafter set forth, the inhibitors of the present invention are comparatively nonvolatile and readily soluble in hydrocarbons. Therefore, these inhibitors also are especially suitable for use in heavier hydrocarbonaceous materials.

In one embodiment the present invention relates to it a method of stabilizing a hydrocarbon which comprises incorporating therein a stabilizing amount of an N,N-disec-aliphaticpphenylene diamineinhibitor in which both aliphatic groups contain at least 8 carbon atoms each.

In a specific embodiment the present invention relates tona method of stabilizing gasoline which comprises incorporating therein from about 0.001% to about 1% by weight of N,N-di-3-(S-methylheptyl)-p-phenylene diamine.

In another specific embodiment the present invention relates to a method of stabilizing petroleum wax which comprises incorporating therein from about 0.0001% to about 5% by weight of N,N-di-4-(2,6-dimethylheptyl)- p-phenylene diamine.

In another embodiment the present invention relates to a hydrocarbon stabilized with an N,N'-di-sec-aliphaticp-phenylene diamine in which both aliphatic groups contain at least 8 carbon atoms each.

The inhibitors of the present invention also are particularly advantageous for use in petroleum wax. In many cases petroleum wax is used in the manufacture of waxed paper or cartons which, in turn, are used for wrapping or boxing food products. In such cases, it is necessary that the Wax contains no components which are toxic because of the possible transfer of such components into the food products. The inhibitors of the present invention are considerably less toxic than the correspond ing p-phenylene diamines substituted with shorter chain alkyl groups and, therefore, offer the important advantage of lowerttoxicity.

It will be noted that the inhibitor of the present invention comprises a specific type of N,N-di-aliphatic-pphenylene diamine. Both aliphathic groups must contain at least 8 carbon atoms each and preferably from 8 to about 20 carbon atoms each. Furthermore, the aliphatic group must be attached to the nitrogen atom at an intermediate carbon atom of the aliphatic group, and this is designated by identifying the aliphatic groups as seealiphatic. Inhibitors having this composition and configuration appear to be of higher potency and to ofier other advantages over the use of substituted phenylene diamine compounds of shorter chain alkyl groups and those in which the alkyl groups are attached at terminal carbon atoms to the nitrogen atoms.

As an illustration of a particular advantage offered by the inhibitor compounds of the present invention as compared to similar compounds containing shorter chain alkyl groups, the inhibitor compounds of the present invention reduce the intake manifold deposits in an automobile engine to approximately one-half of that obtained when using compounds containing shorter alkyl groups. This will be illustrated in Example IV of the present application. The reduction of intake manifold deposits obviousiy is of importance because it permits long time operation of the engine and will not result in plugging of the manifold and accordingly failure of the engine in a shorter period of time.

As hereinbefore set forth, the inhibitors of the present invention are of improved potency in retarding deterionation of hydrocarbons, particularly deterioration caused by oxidation. These inhibitors are comparatively nonvolatile and thereby are retained satisfactorily in the hydrocarbonaceous material. The inhibitors are substantially non-toxic and therefore may be handled safely during preparation and use. Also, the inhibitors may be used safely in petroleum waxes which subsequently are utilized for coating material for containers or wrappers of food products. Still further, these inhibitors are substantially water insoluble and, therefore, will not be lost in the event that the hydrocarbonaceous material contacts water.

The inhibitors of the present invention may be prepared in any suitable manner. In a preferred method, these inhibitors are prepared by the reductive alkylation of p-phenylene diamine or p-nitroaniline with a suitable ketone. When using a ketone for effecting the reductive alkylation, it will be noted that the resultant aliphatic group will be attached at an intermediate carbon atom to the nitrogen atom. Representative ketones suitable for use in the reductive alkylation include methyl isohexyl ketone, methyl heptyl ketone, methyl octyl ketone, methyl nonyl ketone, methyl decyl ketone, methyl undecyl ketone, methyl dodecyl ketone, methyl tridecyl ketone, methyl tetradecyl ketone, methyl pentadecyl ketone, methyl hexadecyl ketone, methyl heptadecyl ketone, methyl octadecyl ketone, methyl nonadecyl ketone, methyl eicosyl ketone, etc., ethyl amyl ketone, ethyl hexyl ketone, ethyl heptyl ketone, ethyl octyl ketone, ethyl nonyl ketone, ethyl decyl ketone, ethyl undecyl ketone, ethyl dodecyl ketone, etc., propyl butyl ketone, propyl amyl ketone, propyl hexyl ketone, propyl heptyl ketone, propyl octyl ketone, propyl nonyl ketone, propyl decyl ketone, propyl undecyl ketone, etc., dibutyl ketone, butyl amyl ketone, butyl hexyl ketone, butyl heptyl ketone, butyl octyl ketone, butyl nonyl ketone, butyl decyl ketone, etc., diamyl ketone, amyl hexyl ketone, amyl heptyl ketone, amyl octyl ketone, amyl nonyl ketone, amyl decyl ketone, etc., dihexyl ketone, hexyl heptyl ketone, hexyl octyl ketone, hexyl nonyl ketone, hexyl decyl ketone, etc.

The reductive alkylation may be effected in any suitable manner. A suitable catalyst for effecting the reaction comprises a mixture of the oxides of chromium, copper and barium, although other suitable catalysts may be employed. Other catalysts include those containing cobalt, nickel, platinum, palladium, molybdenum, etc. In general, the reaction is effected at an elevated temperature of from about to about 250 C. and a hydrogen pressure of from about 5 to about 200 atmospheres.

Preferred inhibitor compounds prepared in the above manner include N,N-di-3-(5 methylhcptyl)-p-phenylene diamine prepared by the reductive alkylation of p-nitroaniline with ethyl isoamyl ketone, N,N'-di-4-(2,6-dimethylheptyl)-p-phenylene diamine prepared by the reductive alkylation using diisobutyl ketone, N,N'-di-2- nonadecyl-p-phenylene diamine prepared by the reductive alkylation using methylheptadecyl ketone formed from stearic and acetic acids. Other representative compounds include N,N-di-2- -1nethylheptyl) -p-phenylene diamine, N,N-di-2-octyl-p-phenylene diamine, N,N'-di-2-(6-methyloctyl)-p-phenylene diamine, N,N'-di-2-nonyl-p-phenylene diamine, N,N-di-2-(7-methylnonyl)-p-phenylene diamine, N,N-di-2-decyl-p-phenylene diamine, N,N-di-2- (4-methyldecyl) -p-phenylene diamine, N,N-di-2- S-methyldecyl -p-phenylene diamine, N,N'-di-2-(4,8-dimethyldecyl)-p-phenylene diamine, N ,N-di-2-undecyl-p-phenylene diamine, N,N-di-2-(5,10-dimethylundecyl)-p-phenylene diamine, N,N-di-2-dodecyl-p-phenylene diamine, N,N'-di-2-(4-methyldodecyl)-p-phenylene diamine, N ,N'-di-2- 4,9-dimethyldodecyl -p-phenylene diamine, N,N'-di-2- (4,7, 1 O-trimethyldodecyl -p-phenylene diamine,

etc., N,N-di-3-octyl-p-phenylene diamine, N ,N-di-3- 5-methyloctyl -p-phenylene diamine, N,N'-di-3- 5 ,7-dirnethyloctyl -p-phenylene diamine, N,N-di-3-nonyl-p-phenylene diamine, N,N-di-3-(7-methylnonyl)-p-phenylene diamine, N,N-di-3-decyl-p-phenylene diamine, N,N'-di-3-(5,9-dimethyldecyl)-p-phenylene diamine, N,N'-di-3- 6-ethyldecyl -p-phenylene diamine, N,N-di-3-undecyl-p-phenylene diamine, N,N'-di-3-(9-methylundecyl)-p-phenylene diamine, N,N'-di-3- 6,9-diethylundecyl -p-phenylene diamine, N,N'-di-3-dodecyl-p-phenylene diamine, N,N-di-3-(6-methyldodecyl)-p-phenylene diamine, N,N-di-3-( 10-ethyldodecyl)-p-phenylene diamine, N,N'-di-3-(5-ethyl-l l-methyldodecyl) -p-phenylene diamine, etc.

When the aliphatic groups comprise alkenyl groups, the inhibitor may be prepared by the reaction of p-phenylene diamine or p-nitroaniline with a suitable unsaturated ketone including, for example, vinyl amyl ketone, phorone, vinyl hexyl ketone, vinyl heptyl ketone, vinyl octyl ketone, vinyl nonyl ketone, vinyl decyl ketone, vinyl undecyl ketone, vinyl dodecyl ketone, vinyl tridecyl ketone, vinyl tetradecyl ketone, vinyl pentadecyl ketone, etc. Representative examples of inhibitors in this class are N,N-di-3-(1-octenyl)-p-phenylene diamine, N,N-di-4- (2,6-dimethyl-2,S-heptadienyl)-p-phenylene diamine, etc. This reaction is effected in substantially the same manner as hereinbefore set forth and, depending upon the extent of hydrogenation, the product may comprise N,N- dialkenyl-p-phenylene diamine or a mixture of an N,N'- dialkenyl-p-phenylene diamine and N,N-dialkyl-p-phenylene diamine.

It is understood that the various inhibitors which may be prepared and used in accordance with the present invention are not necessarily equivalent in the same or different hydrocarbons but all of them will be effective in retarding oxidative deterioration thereof.

The inhibitor of the present invention may be incorporated in the hydrocarbon in any suitable manner. When the hydrocarbon is a liquid, the inhibitor compound may be readily dissolved therein and preferably is followed by suitable mixing in order to obtain complete mixing of the inhibitor with the hydrocarbon. Similarly, when the hydrocarbon is a solid, the inhibitor may be dissolved therein by suitable mixing and, when desired, mild heating of the hydrocarbon followed by suitable mixing. When the inhibitor compound is a solid, it may be dissolved in the hydrocarbon as such or it may be dissolved in a suitable solvent including hydrocarbon, ketone, ether, etc., or the inhibitor compound may be heated to liquefy it and then utilized as a liquid.

In general, the inhibitor will be used in an amount of from about 0.000 l% to about 5% by weight of the hydrocarbon, although in some cases lower or higher concentrations may be employed. The exact concentration to be used will depend upon the particular hydrocarbon fraction being treated. In most cases, concentrations of from about 0.0001% to about 1% and more particularly from about 0.001% to about 1% by weight generally will be employed.

When desired, the inhibitor of the present invention may be used along with other additives incorporated in the hydrocarbon fraction. The other additives will depend upon the particular hydrocarbon fraction being treated. For example, in gasoline a metal deactivator, tetraethyl lead, dye, etc., may be incorporated in the gasoline. When incorporated in wax for subsequent use in contact with food products, various supplementary nontoxic inhibitors, synergists, etc. are employed. In any event, it is understood that other antioxidants may be used along with the inhibitor of the present invention and, when desired, the inhibitor and other additives may be prepared as a mixture with one or more of these additives and incorporated in this manner in the hydrocarbon fraction.

The following examples are introduced to illustrate further the novelty and utility of the present invention but not with the intention of unduly limiting the same.

Example I 0.05% by weight of N,N'-di-4-(2,6-dimethylheptyl)- p-phenylene diamine is incorporated in petroleum wax. This serves to retard oxidative deterioration of the wax.

Example II N,N-di-3-(S-methylheptyl)-p-phenylene diamine is incorporated in petroleum wax in a concentration of 0.01

by weight. The petroleum wax containing the inhibitor is used in the manufacture of waxed paper. As hereinbefore set forth, the inhibitor is of comparative low toxicity and therefore is satisfactory for use in wax which, in turn, is used to prepare waxed paper for use as wrapping for food products.

Example Ill N,N di-3-(5-methylheptyl)-p-phenylene diamine is used in a concentration of 0.01% by weight to stabilize a Pennsylvania cracked gasoline having an uninhibited induction period of minutes. Upon the addition of the inhibitor as hereinbefore set forth, the induction period of the gasoline is increased sufiiciently for satisfactory use of the gasoline.

Example IV As hereinbefore set forth, a particular advantage to the use of the inhibitor compounds of the present invention is the reduction in intak manifold deposits. This is illustrated in comparative tests conducted with a gasoline comprising a blend of catalytic reformed, straight run and thermally cracked gasolines, the blend having an ASTM gum content of 6 mg. These runs were made in a Chevrolet engine operated at the following conditions:

Speed r.p.m 2500 Load B.H.P 30 Jacket temp. F 95 Oil temp F Air-fuel ratio FL- 14.5 Duration hours 60 above described and the intake manifold deposits were measured. These results are reported below:

Deposit Additive: grams None 7 24.9

N,N'-di-sec butyl-p-phenylene diamine 12.4 N,N'-di-3-(5-methylheptyl)-p-phenylene diamine 6.2

From the above data, it will be noted that the intake manifold deposits were reduced approximately one-half by the addition of N,N'-di-sec butyl-p-phenylene diamine. While this is an important reduction in the intake manifold deposits, it will be noted that N,N'-di-3-(5-methylheptyl)-p-phenylene diamine reduced the intake manifold deposits to approximately one-quarter of that obtained with the control sample of gasoline and to approximately one-half of that obtained with the gasoline containing N,N-di-sec-butyl-p-phenylene diamine. As hereinbefore set forth, this reduction in intake manifold deposits is of importance and serves to prolong the satisfactory operation of the engine.

We claim as our invention:

1. Petroleum wax normally subject to oxidative deterioration containing a stabilizing amount of N,N'-di-secalkyl-p-phenylene diamine inhibitor in which each of the alkyl groups contains from 8 to about 20 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 2,451,642 Watson Oct. 19, 1948 2,496,930 Brimer Feb. 7, 1950 2,498,630 Thompson Feb. 28, 1950 2,599,794 Weber June 10, 1952 2,692,288 Bell Oct. 19, 1954 2,694,034 Moriarity Nov. 9, 1954 2,729,691 De Pree Jan. 3, 1956 2,833,634 Hill May 6, 1958 

5. PETROLEUM WAX NORMALLY SUBJECT TO OXIDATIVE DETERIORATION CONTAINING FROM ABOUT 0.001% TO ABOUT 5% BY WEIGHT OF N,N''-DI-SEC-ALKYL-P-PEHNYLENE DIAMINE INHIBITOR IN WHICH EACH OF THE ALKYL GROUPS CONTAINS FROM 8 TO ABOUT 20 CARBON ATOMS. 